GB2444825A

GB2444825A - A lubricating fluid feed in a transmission

Info

Publication number: GB2444825A
Application number: GB0723675A
Authority: GB
Inventors: Jim Thomas Gooden; Norman Jerry Bird; Ernest Russell Shedd; John William Kimes
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2006-12-12
Filing date: 2007-12-04
Publication date: 2008-06-18
Anticipated expiration: 2027-12-04
Also published as: GB0723675D0; US20080135370A1; CN101201082B; CN101201082A; GB2444825B; US7690492B2

Abstract

A component, e.g. a clutch ring or hub 70 in a one-way clutch, surrounding an axis 23 is arranged to direct fluid along a flow path in a transmission for a motor vehicle. The clutch ring 70 includes a first wall 74 having an inner surface 76 facing the axis 23, a number of holes 80 spaced about the axis 23 each of which extends through the first wall 74 and a channel 82 formed in the first wall 74 each communicating with one of the holes 80. Channels 82 have a base 84 with a length that extends angularly about the axis 23 and a depth that decreases along the length as the distance from the hole 80 increases. The channels 82 are open to permit lubricating fluid flow into the channel 82 and channels 82 have a maximum depth at the holes 80.

Description

A FLUID FEED FOR A MOTOR VEHICLE TRANSMISSION

This invention relates generally to supplying hydraulic fluid, such as lubricant, to a component and in particular to a fluid flow path in a rotating hub of cJutch for a motor vehicle transmission.

The hub of a friction clutch or an overrunning clutch in an automatic transmission assembly transfers torque between an element of the clutch element and a shaft or another component that transmits torque in the assembly. In addition, such hubs carry hydraulic fluid, such as automatic transmission fluid (ATF), to lubricate and cool surfaces of the clutch, especially those surfaces that are subject to friction, fretting or chafing during in-service use. To provide fluid passageways, the hub is usually formed with a series of angularly spaced holes drilled radially through the hub thickness, through which holes fluid passes to the critical surfaces of the component. ATF fluid is continually deposited by being thrown radially outward against the inner surface of the component as the assembly operates.

Typically, hubs that are machined from a solid metal blank or forging, or by another forming method other than sheet metal forming, require machining an oil dam on the inner diameter of the hub to direct oil through radial drilled holes in order to cool the clutch and to prevent oil flow from the ends of the hub. Oil dams are, however, expensive to machine in such hubs.

Axially directed slots located at each radial hole are ineffective toward directing a sufficient volume of oil from the inside diameter of the hub to the radial holes because oil delivered to the hub inner diameter along the circumferential iength of the hub between the slots will run off the end of the hub instead of flowing into the axial slots and radial holes.

It is an object of the invention to provide a low cost technique that efficiently and etfectively gathers and transports oil from the inner circumference of a hub to and through holes that pass through the wall thickness of a hub to facilitate lubrication and cooling of the critical surface of the component.

According to the invention there is provided component for directing fluid along a flow path in a transmission for a motor vehicle, the component comprising a wall surrounding an axis having an inner surface facing the axis and at least one hole extending through the first wall and at least one channel formed in the wall each channel communicating with a respective hole and the inner surface wherein each channel has a base portion having a length that extends angularly about the axis and a depth that decreases along the length of the base portion as distance from the hole increases.

There may be a number of holes mutually spaced about the axis, each of the holes extending through the thickness of the first wall and there may be a number of channels formed in the wall, each channel communicating with a respective one of the holes and the inner surface.

Each hole may extend radially through the first wall.

The axis may be an axis of rotation of the component.

The component may further comprise a wall located at a first axial end of each channel for closing each channel against fluid flow past the wall.

One end of each channel may be open to permit fluid to flow into the channel.

The depth of each channel may be a maximum at the hole.

The length of each channel may extend circumferentially to only one side of its respective hole.

The base of each channel may extend angularly on both sides of a radial line which extends from the axis through the centre of each hole.

The component may be a clutch ring supported for rotation about the axis or alternatively, the component may be a clutch hub that rotates about the axis in a transmission for a motor vehicle.

The invention will now be described by way of example with reference to the accompanying drawing of which:-

Figure 1 is a side view showing a prior art

hydraulically actuated clutch and servo in an automatic transmission assembly; Figure 2 is an isometric view of a clutch ring according to the invention illustrating its hub and inner surfaces; Figure 3 is an end view of a clutch component according to the invention showing a fluid channel; Figure 4 is a cross section taken at plane 4-4 of Figure 3; Figure 5 is an end view of a component similar to that shown in Fig.3 but showing an alternate fluid channel; Figure 6 is a cross section taken at plane 6-6 of Figure 5; Figure 7 is a partial isometric view illustrating the fluid channel of Figure 3 formed on the inner surfaces of a clutch ring; and Figure 8 is a partial isometric view illustrating the fluid channel of Figure 4 formed on the inner surfaces of a clutch ring.

Referring first to Figure 1, a clutch 10 ( in the form of a multi-pilate wet clutch) for alternately opening and closing a drive connection between a hub 12 and a drum member in the form of a clutch cylinder 14 in a s hydraulically-actuated automatic transmission includes clutch plates 16, mutually spaced axially along the drum 14.

The radial outer periphery of the plates 16 are connected to the drum by a spline drive 17 formed on the inner surface of drum 14, such that the plates and drum 14 rotate as a unit. Located between each of the plates 16 is a friction disc 18, which is connected to the hub 12 by a spline drive 19 formed on the radial outer surface of the hub 12 such that the discs 18 and hub 12 rotate as a unit.

The hub 12 is supported on a bearing 20 and is formed with a series of angularly-spaced radial holes 22, through which hydraulic fluid passes radially outward to the friction discs 18 and plates 16. The clutch is substantially symmetric about a longitudinal axis 23.

The clutch plates 16 and friction discs 18 are forced into mutual frictional content by movement of a servo piston 24, located in a cylinder defined by drum 14. Chamber 26 is supplied with a pressurized hydraulic fluid through a passage 28 and check valve 30. When cylinder 26 is pressurized, piston 24 moves rightward forcing plates 16 and discs 18 against a pressure plate 32, which is engaged with spline drive 17 and is secured by a snap ring 34 to the drum 14. In this way, plates 16 and discs 18 produce a drive connection between hub 12 and drum 14. A return spring 36 continually applies to piston 24 a force that resists its movement rightward and causes the piston to move leftward to the position shown in Figure 1, when pressure in cylinder 26 is low. The position of compression return spring 36 is fixed by a plate 38, which is secured by a snap ring 40 to a hub 42. A check valve 30 allows oil to exit the chamber 26 when pressure is low to reduce centrifugal forces from the residual oil in the chamber and ensure leftward movement of the piston 24 when intended.

Figure 2 is an isometric view of a ring for a one-way clutch. The ring 50 includes a huh 52, which extends angularly about axis 23, the hub 52 being formed with five angularly-spaced axial holes and a large central hole 57.

A portion of the outer surface of ring 50 is formed with axially directed spline teeth 58, similar to the spline teeth used in the spline drives 17, 19, which driveably connect the plates 16 and discs 18 of clutch 10 to the drum 14 and hub 10. Another portion of the outer surface of ring 50 is formed with cam surfaces 60, which can be engaged by rockers of a one-way clutch, such as those described and illustrated in U.S. Patent 7,100,756.

Extending axially parallel to axis 23 and located on the radial inner surface opposite spline 58 are the surfaces which as described in detail with reference to Figures 3-form fluid guides. A series of angularly spaced radial holes 80 pass through the axial wall 74, 94 to transfer the fluid guided to them.

Referring to Figures 3 and 4, a clutch ring component arranged about the central axis 23 includes a circumferentially extending wall 74 having an inner surface 76, which faces the central axis 23 and an outer surface 78 which faces away from the central axis. A series of radial holes 80 are mutually angularly spaced about the axis 23 and extend through the wall 74.

Fluid channels 82, formed in the wall 74, are mutually spaced about axis 23. Each channel 82 includes a base 84, which extends angularly toward a respective hole 80. The depth of each channel 82, as measured by the radial distance between the inner surface 76 and the base 84, increases as the angular distance along the base from the respective hole decreases so that the depth of each channel 82 is a maximum at the respective hole 80.

The base 84 of each channel 82 terminates at a surface 86, which intersects both the base and the inner surface 76 and each channel 82 communicates with the respective hole 80.

As Figure 4 illustrates, at one end face 87 of wall 74, each channel 82 is closed by the radial hub 52. At the opposite axial end of face 88, each channel 82 is open to permit tool extraction so that these features can be formed by the initial manufacturing process.

In operation, preferably component 70 rotates counterclockwise about axis 23. Hydraulic fluid, thrown radially outward against inner surface 76 as the component 70 rotates, enters each channel 82 along its entire angular length between adjacent holes 80, flows in the channel toward and through the respective hole 80 at the end of the channel 82.

Referring to Figures 5 and 6, a clutch ring component arranged about the central axis 23, includes a circumferentially extending wall 94 having an inner surface 96 which faces the central axis 23 and an outer surface 98 which faces away from the central axis 23. A series of holes 80 mutually angularly spaced about axis 23 extend radially through the wall 94.

A number of fluid channels 102 formed in the wall 94 are mutually spaced about axis 23. Each channel 102 includes a base 104 which extends angularly toward a respective hole 80. The base 104 of each channel 82 extends angularly on both sides of a radial line, which extends from axis 23 through the centre of each hole 80 from the base of an adjacent channel to the hole of the subject channel. The depth of each channel 102, as measured by the radial distance between inner surface 96 and the base 104, increases as the angular distance along the base from the respective hole 80 decreases so that the depth of each channel 102 is a maximum at the respective hole 80 and each of the channels 102 communicates with its respective hole 80. Each hole 80 has two channels 102 communicating with it.

As Figure 6 illustrates, at one end face 108 of wall 94, each channel 102 is closed by radial hub 52. At the opposite axial end face 112, each channel 102 is open to permit fluid to flow into the channel 102 along its length toward the hole 80 and though the hole 80 to the outer surface 98.

In operation, the component 90 rotates in either direction about axis 72. Hydraulic fluid, thrown radially outward against inner surface 96 as component 90 rotates, enters each channel 102 along its entire angular length between adjacent holes 80, flows in the channel in both angular directions toward and through the respective hole 80 at the end of the channel 82. This embodiment is therefore no affected by the direction of rotation of the component 90.

Therefore in summary, the invention provides a hub

formed with a series of fluid channels, each having a base located at the inner radial surface of the hub where ATF, or another hydraulic fluid, is continually deposited by being thrown radially outward as the assembly rotates. Each channel has a base, whose contour collects oil along substantially the entire angular length of the inner surface between adjacent channels. The channels are formed such that they eliminate or reduce the need for machining the inner surface of the hub or race of an overrunning clutch.

Rather than using axial slots, the profile of each channel's base has the appearance of a cam, similar to that of a ratcheting, mechanical one-way clutch. The channel base directs oil to the major diameter of the channel, where a radial uhe hole is located such that all oil delivered to the hub inner diameter is directed through the radial oil holes instead of only that portion of the oil contained in axial slots having a narrow angular length.

The contour of the channel's base in one embodiment referred to with respect to Figs 3, 4 and 7 is formed to :5 operate with a hub that rotates in one direction only so that the end of the channel terminates at a radial hole and the depth of the channel is a maximum at the hole.

In an alternative embodiment referred to with reference to Fi.gs.2, 5, 6 and 8 the contour of each channel's base extends is opposite angular direction from a respective hole to accommodate hubs that rotate in opposite directions and the depth of each channel is a maximum at the respective hole.

Claims

1. A component for directing fluid along a flow path in a transmission for a motor vehicle, the component comprising a wall surrounding an axis having an inner surface facIng the axis and at least one hole extending through the first wall and at least one channel formed in the wall each channel communicating with a respective hole and the inner surface wherein each channel has a base portion having a length that extends angularly about the axis and a depth that decreases along the length of the base portion as distance from the hole increases.

2. A component as claimed in claim 1 wherein there are a number of holes mutually spaced about the axis, each of the holes extending through the thickness of the first wall and there are a number of channels formed in the wall, each channel communicating with a respective one of the holes and the inner surface.

3. A component as claimed in claim 1 or in claim 2 wherein each hole extends radially through the first wall.

4. A component as claimed in any of claims 1 to 3 wherein the axis is an axis of rotation of the component.

5. A component as claimed in any of claims 1 to 4 wherein the component further comprises a wall located at a first axial end of each channel for closing each channel against fluid flow past the wall.

6. A component as claimed in any of claims I to 5 wherein one end of each channel is open to permit fluid to flow Into the channel.

7. A component as claimed in any of claims 1 to 6 wherein the depth of each channel is a maximum at the hole.

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8. A component as claimed in any of claims 1 to 7 wherein the length of each channel extends circumferentially to only one side of its respective hole

9. A component as claimed in any of claims 1 to 7 wherein the base of each channel extends angularly on both sides of a radial line which extends from the axis through the centre of each hole.

10. A component as claimed in any of claims 1 to 9 wherein the component is a clutch ring supported for rotation about the axis.

11. A component as claimed in any of claims 1 to 9 wherein the component is a clutch hub that rotates about the axis in a transmission for a motor vehicle.

12. A component for directing fluid along a flow path in a transmission for a motor vehicle substantially as described herein with reference to figures 2 to 8 of the accompanying drawing.